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Infrared structural characterization of single grains from two Apollo 15 dusts.
Estep PA; Kovach JJ; Karr CL Jr.
The Apollo 15 Lunar Samples. Chamberlain JW, Watkins C, eds. Houston, TX: Lunar Science Institute, 1972 Oct; :470-474
Single grains (>150u) of minerals, basalts, and glasses from two Apollo 15 dusts have been structurally characterized by infrared absorption spectroscopy. The two comprehensive dusts were obtained from geologically different terrains--sample 15301,83 from the Apennine front on the northeast rim of Spur Crater (Station 7), and lying on a narrow ridge that may be a ray formed from the craters aristillus or autolycus; and sample 15601,72, from the Mare-Rille terrain, collected approximately 20 meters northeast of the rim of Hadley Rille (Station 9A), lying off the ridge. The infrared spectral data show that grains from each dust have distinctive structural features that characterize the site of collection and may help to interpret its geology. Structural features of grains from the front dust were similar to those in grains that were previously isolated from Apollo 14 Fra Mauro Highland samples, while those from the Rille dust were similar to those that were observed in grains from Apollo 11 and 12 Mare basaltic samples. Differences between the two Apollo 15 samples as determined by single-grain infrared analyses may further serve to distinguish ray material from nonray material. The dusts were dry-sieved and single grains isolated from only the +100 mesh fractions. The front dust gave a smaller amount of +100 mesh (15.5 weight-percent) than the Rille dust (32.6 weight- percent), or any of the six other dusts that we previously studied from Apollo 11, 12, and 14 missions (21.7 to 32.1 weight-percent). Infrared analyses for single grains from the dusts, as shown in table 1, were obtained by recently developed microsampling techniques. These made it possible to detect grain-to-grain structural variations in several different mineral classes within each dust sample and to characterize the structures of some trace accessory minerals.
Mineral dusts; Sampling methods; Sampling
Chamberlain JW; Watkins C
The Apollo 15 Lunar Samples
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